Medical electronic devices have become indispensable. Such devices include a hearing aid as well. A hearing aid is a device for aiding an individual in regard to his or her hearing. It is generally used to compensate a hearing loss, namely a conventional acoustic hearing aid amplifying sound, or a cochlear implant that electrically stimulates nerve cells or a bone conduction hearing aid. It may also be a hearing protection device which helps individuals to hear without damage in noisy environments. It may also be a tinnitus treatment device.
BTE hearing aid units such as traditional BTE hearing aids comprise a partially longitudinal, hook-shaped shell running substantially along a longitudinal axis and containing electronic components within the shell. One shell end, usually the tapering end, constitutes the ear hook that is used to rest the hearing aid unit on and behind a user's ear. Generally, the shell is made of two lengthwise parts that are joined together to form the shell. The electronic components are placed on top of inner surface of one of the parts before the two parts are joined together. This type of shell suffers from a number of drawbacks:    i) because the shell includes two parts, the shell may be weaker along the line where two parts are joined together and thus susceptible to breakage;    ii) additional sealing material is required along the line where the two parts join.
However, despite the sealing provided along the line where the two parts are joined together, the shell is vulnerable to dirt and liquid including user's sweat entering the shell along the line because parting lines of this nature are very difficult to seal. Ingress of liquid inside the shell may even lead to corrosion of electronic components and possibility of a short circuit, and    iii) the assembly of the electronic components need to precise in order to reliably join the two parts together.
The disclosure proposes a solution that overcomes the aforementioned drawbacks.